JP2001042246A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to irradiate an object with a beam of light with high positional accuracy even if a stage is displaced in the Y-axis direction due to vibrations, etc. SOLUTION: A Y-position detector 2 measures the distance up to a stage 1 and detects the position of the stage in the Y-axis direction. A stage position setting circuit 4 outputs a signal representing the distance between the Y-position detector 2 and the stage 1 when stage 1 is not displaced according to the data supplied by a CPU 3. A compactor 5 calculates the difference between this signal and the signal representing the distance between the stage and the Y- position detector outputted by the stage position setting circuit 4 and outputs the result to a gain adjusting circuit 10. The gain adjusting circuit 10 adjusts the output signal level of the comparator 5, and supplies the signal to an adder 7. The adder 7 adds the output signal of the gain adjusting circuit 10 to an electric signal from a scanner position setting circuit 6, thereby corrects the electric signal from the scanner position setting circuit 6 and supplies the signal to a scanner driving circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanner device which irradiates an object placed on a stage with light and scans the light while moving the stage.

[0002]

2. Description of the Related Art In a laser processing apparatus or the like, an object is placed on a stage and moved in the X-axis direction. In this state, the object is irradiated with a laser beam, and the irradiation position is changed to a Y-axis orthogonal to the X-axis direction. It is often performed to move repeatedly within a specific range in the direction, and for this purpose, an optical scanner device is used. FIG. 10 is a block diagram showing an example of a conventional optical scanner device. This optical scanner device 1
In 02, a light irradiation target (not shown) is arranged on the stage 1, and the target is irradiated with a laser beam from a laser oscillator (not shown). A scanner driving mechanism 9 is interposed between the laser oscillator and the object. The stage 1 is driven under the control of the CPU 3 and moves in the X-axis direction. The X position detector 11 detects the position of the moving stage 1 and outputs a signal representing the detection result. The scan interval detection circuit 12 outputs a signal from the X position detector 11 and C
The scan timing signal is output each time the stage 1 moves by ΔX based on the data of the movement pitch ΔX given from the PU 3.

The scanner position setting circuit 6 stores data on the irradiation position of the laser beam in the Y-axis direction in the CPU 3.
And outputs an electric signal indicating the irradiation position in the Y-axis direction each time the scan interval detection circuit 12 outputs a scan timing signal. The scanner drive circuit 8 power-amplifies the electric signal and performs a scanner driving mechanism 9.
To supply. The scanner driving mechanism 9 includes, for example, a mirror that reflects the laser beam from the laser oscillator and a galvanometer that oscillates the mirror. The galvanometer is driven by the scanner drive circuit 8, and the mirror oscillates. The laser beam is deflected and scanned.

FIG. 4 is a plan view for explaining scanning of a beam spot on an object to be irradiated with a laser beam. The irradiation target is placed on the stage 1 and moves in the X-axis direction, and the scanning in the Y-axis direction is repeated each time the scan interval detection circuit 12 outputs a scan timing signal.
As a result, in the rectangular area 101 on the irradiation target, the interval is Δ
A laser beam is irradiated at each position X0, X1, X2,... Of X, and the laser beam is scanned in the Y-axis direction at each position. In the figure, each straight line 104 indicates the scanning locus of the laser beam spot.

[0005]

However, in such a conventional optical scanner device 102, the stage 1 is subjected to vibrations from the outside or a servomotor is driven in accordance with the position control of the stage 1, so that the stage 1 is moved. Tweak,
The stage 1 may be slightly displaced in the Y-axis direction. When the stage 1 is moved in the X-axis direction as described above, the stage 1 may be slightly displaced in the Y-axis direction.

When the stage 1 is displaced in the Y-axis direction in this manner, the irradiation object is displaced similarly. For example, in the example of FIG. Relative displacement, rectangular area 1
01 will not be correctly irradiated with the laser beam. Therefore, in the case of a laser processing apparatus, an area to be processed cannot be processed with high accuracy, and when such an optical scanner apparatus 102 is used in an inspection apparatus, an original area can be accurately inspected. Can not. Further, when an image of an irradiation target is acquired by the optical scanner device 102, it is difficult to accurately acquire an image of a target area.

An object of the present invention is to solve such a problem. An object of the present invention is to provide an optical scanner device capable of irradiating a target with light with high positional accuracy even if the stage is displaced in the Y-axis direction due to vibration or the like. Is to provide.

[0008]

In order to achieve the above object, the present invention provides a stage on which a light irradiation object is mounted, a stage driving means for moving the stage in the X-axis direction, and an object on the stage. Light scanning means for irradiating light on the basis of a given electric signal to move a light irradiation position in a direction of a Y-axis substantially orthogonal to the X-axis. An optical scanner device that irradiates the object with light by the optical scanning unit and moves the light irradiation position repeatedly within a specific range in the Y-axis direction while moving the stage in the Y-axis direction. Position detecting means for detecting the position, and based on the detection result of the position detecting means, so that the light irradiation position moves within the specific range, the electric signal given to the light scanning means Characterized by comprising a positive scanning position correction means.

In the optical scanner of the present invention, the position detecting means detects the position of the stage in the Y-axis direction, and the scanning position correcting means sets the light irradiation position in the Y-axis direction based on the detection result of the position detecting means. The electric signal given to the optical scanning means is corrected so as to move within a specific range. Then, the light scanning means moves the light irradiation position based on the corrected electric signal. Therefore, even if the stage is displaced in the Y-axis direction due to vibration applied from the outside or the drive of the servomotor accompanying position control, or even if the stage is displaced in the Y-axis direction due to the movement of the stage itself in the X-axis direction, Since the light irradiation position of the light in the Y-axis direction is corrected according to the displacement, the light is always irradiated on a light irradiation target in a certain range in the Y-axis direction.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the optical scanner device according to the present invention. In the figure, FIG.
Elements that are the same as 0 are denoted by the same reference numerals, and a description thereof will be omitted here. The optical scanner device 14 shown in FIG. 1 is different from the optical scanner device 102 of FIG. 10 in that a Y position detector 2, a stage position setting circuit 4,
The point is that a comparator 5, a gain adjustment circuit 10, and an adder 7 are newly provided.

In this embodiment, the Y position detector 2 (position detecting means according to the present invention) is constituted by a length measuring system using an optical interferometer, and irradiates a laser beam to the side of the stage 1 and reflects the reflected light. The position of the stage 1 in the Y-axis direction is detected by receiving the light and precisely measuring the distance to the stage 1. The CPU 3 previously holds data on the distance between the Y position detector 2 and the stage 1 in the Y-axis direction when the stage 1 is not displaced in the Y-axis direction,
The data is supplied to the stage position setting circuit 4. The stage position setting circuit 4 outputs a signal indicating the distance between the Y position detector 2 and the stage 1 based on the data supplied from the CPU 3.

The comparator 5 outputs from the Y position detector 2;
A signal indicating the distance between the stage 1 and the Y position detector 2 and the stage 1 and Y output by the stage position setting circuit 4
The difference from the signal indicating the distance to the position detector 2 is calculated, and the result is output to the gain adjustment circuit 10. The gain adjustment circuit 10 amplifies or attenuates the output signal of the comparator 5 to an appropriate level and supplies the output signal to the adder 7. Specifically, the gain adjustment circuit 10 adjusts the amplitude of the output signal of the comparator 5 so that the resolution of the distance in the output signal of the comparator 5 and the position setting resolution in the scanner driving mechanism 9 are substantially the same. I do. The adder 7 corrects the electric signal from the scanner position setting circuit 6 by adding the output signal of the gain adjustment circuit 10 to the electric signal from the scanner position setting circuit 6 (scanning position setting means according to the present invention). , And the scanner drive circuit 8.

FIG. 2 is a side view showing the periphery of the stage 1, and FIG.
3 is a plan view showing the periphery of the stage 1. FIG. As shown in FIGS. 2 and 3, an object 1 to be irradiated with light is placed on a stage 1.
9, a scanner driving mechanism 9 is disposed above it (FIG. 2). The scanner driving mechanism 9 is a mirror 1 that reflects a laser beam 13 from a laser oscillator (not shown).
8 and a galvanometer (not shown) that drives the mirror 18 to swing. The galvanometer is driven by electric power supplied from the scanner drive circuit 18 to swing the mirror 18. In this case, the scanner driving mechanism 9 determines that the displacement of the stage 1 to be corrected is 1
It is assumed that the laser beam 13 can be scanned 100 times or more during the period. However, the number of scans should be increased or decreased depending on the required correction accuracy.

An interference measurement length system 17 constituting the Y position detector 2 is disposed on the side of the stage 1 and emits a laser beam toward the side surface of the stage 1 in parallel with the Y-axis direction. The length measuring system 17 receives the reflected light of the laser light from the side surface of the stage and detects the distance to the stage 1. An X drive unit 16 (FIG. 3) is also provided on the side of the stage 1 to move the stage 1 in the X-axis direction. A Y drive unit 15 installed on the side of the stage 1 opposite to the length measuring system drives the stage 1 in the Y-axis direction under the control of the CPU 3 to perform positioning of the stage 1 in the Y-axis direction. Note that the comparator 5, the gain adjustment circuit 10, and the adder 7 constitute a scanning position correction unit according to the present invention.

Next, the operation of the optical scanner device 14 configured as described above will be described. Under the control of the CPU 3, the stage 1 is driven by the X drive unit 16 as shown in FIG.
To move in the X-axis direction. X position detector 1
1 (second position detecting means according to the present invention) detects the position of the stage 1 moving in this way in the X-axis direction, and the scan interval detecting circuit 12 sets a scan timing every time the stage 1 moves ΔX. Output a signal. The scanner position setting circuit 6 receives data on the irradiation position of the laser beam 13 in the Y-axis direction from the CPU 3, and every time the scan interval detection circuit 12 outputs a scan timing signal, the scanner position setting circuit 6 outputs an electric signal indicating the irradiation position in the Y-axis direction. Output a signal.

The adder circuit corrects the electric signal with the output signal of the gain adjustment circuit 10, and the scanner drive circuit 8 power-amplifies the corrected electric signal and supplies it to the scanner drive mechanism 9. In the scanner driving mechanism 9, the galvanometer swings and drives the mirror 18 shown in FIG. 2, and as a result, the laser beam 13 is deflected and scanned.

In FIG. 3, the stage 1 indicated by a dotted line is for the first scanning of the laser beam, and the stage 1 indicated by a solid line is for the second scanning. And
The thin line rectangle 20 is the object 1 at the time of the first laser beam scanning.
9 and the bold rectangle 21 indicates the position of the object 19 during the second laser beam scanning. Also, line 2
2 indicates a scanning position at the time of the first scanning, and a straight line 23 indicates a scanning position at the time of the second scanning. The interval between the straight lines 22 and 23 is ΔX.

If it is assumed that vibration or the like is applied to the stage 1 from the outside, as shown in FIG. 3, the position of the stage 1 at the time of the second scanning shown by the solid line is equal to the position of the first scanning shown by the dotted line. The position is slightly displaced, for example, in the minus direction of the Y axis with respect to the position of the stage 1 at the time of scanning. Then, as shown in FIGS. 2 and 3, the length measuring system 17 constituting the Y position detector 2 detects L2 as the distance to the stage 1 during the first scan, but detects the distance L2 during the second scan. A distance L1 slightly longer than L2 is detected, and a signal representing the detected distance is output.

The CPU 3 previously holds data on the distance between the Y position detector 2 and the stage 1 in the Y-axis direction when the stage 1 is not displaced in the Y-axis direction, that is, data on the distance L2. The data is supplied to the stage position setting circuit 4. The stage position setting circuit 4 includes a CP
With this data supplied from U3, the Y position detector 2
And outputs a signal indicating the distance between the stage and stage 1.

The comparator 5 outputs from the Y position detector 2,
The difference ΔL between the signal indicating the distance L1 between the stage 1 and the Y position detector 2 and the signal output from the stage position setting circuit 4 indicating the distance L2 between the stage 1 and the Y position detector 2
And outputs a signal representing ΔL to the gain adjustment circuit 10. The operation by the comparator 5 can be represented by the following equation.

[0021]

ΔL = L1−L2 The gain adjustment circuit 10 determines the ΔL so that the resolution of the distance in the output signal of the comparator 5 and the position setting resolution in the optical scanner driving mechanism are substantially the same. , And outputs a signal representing the adjusted distance difference ΔP. Here, assuming that the gain constant in the gain adjustment circuit 10 is α, ΔP is represented by the following equation.

[0022]

ΔP = α × ΔL The adder 7 adds the output signal of the gain adjustment circuit 10 to the electric signal from the scanner position setting circuit 6 to correct the electric signal from the scanner position setting circuit 6, It is supplied to the scanner drive circuit 8. As a result, the second scanning position is accurately performed within the range of the object 19 as shown by the straight line 23 in FIG. 3, even though the stage 1 is displaced in the Y-axis direction by ΔL. .

FIG. 5 is a waveform diagram showing a change in the displacement of the stage 1 in the Y-axis direction as the stage 1 moves. FIG. 6 shows the corrected laser beam 13 when the stage 1 is displaced as shown in FIG. FIG. 4 is an explanatory diagram showing a change in a scanning position. FIG. 8 is a waveform diagram showing a change in the output signal of the gain adjustment circuit 10 when the stage 1 is displaced in the Y-axis direction with the movement of the stage 1, and FIG. FIG. 8 is a waveform diagram illustrating an output signal of an adder 7 when the signal changes as shown in FIG. FIG. 7 is a waveform diagram showing a signal supplied to the scanner drive circuit 8 when the output signal of the scanner position setting circuit 6 is not corrected.

When the stage 1 moves further in the X-axis direction, the stage 1 is displaced in the plus or minus direction of the Y-axis due to external vibration or the like. Therefore,
At this time, the ΔL calculated by the comparator 5 changes like a curve 200 shown in FIG. Then, ΔL that changes in this manner is adjusted by the gain adjustment circuit 10 and output as ΔP. Therefore, ΔP also changes in the same manner as ΔL, as indicated by the curve 24 in FIG.

Thereafter, the output signal of the scanner position setting circuit 6 is corrected based on ΔP thus changed, so that the output signal P of the adder 7 changes as shown by a waveform 26 in FIG. A curve 28 connecting the maximum point and the minimum point of the waveform 26 respectively changes similarly to the curve 24 shown in FIG. The solid line portion of the waveform 26 is the laser beam 1
3 corresponds to each scanning period.

Since the scanner drive circuit 8 drives the scanner drive mechanism 9 based on the output signal of the adder 7, the straight line 30 representing the scanning trajectory for each scan is:
As shown in FIG. 6, it is displaced in the Y-axis direction.
A curve 32 connecting the start point and the end point of the straight line 30 has a waveform similar to the curve 20 in FIG. An area between the two curves 32 corresponds to a scanning area on the object 19.

When the output signal of the scanner position setting circuit 6 is not corrected, as shown in FIG. 7, the scanner drive circuit 8 always keeps the positions of the minimum point and the maximum point in each scan at a fixed value. When the stage 1 is displaced in the Y-axis direction as represented by ΔL in FIG. 5, the scanning position is shifted with respect to the object 19. On the other hand, in the present embodiment, the scanning position of the laser beam 13 is corrected in accordance with the displacement of the stage 1, so that the laser beam 13 is accurately irradiated on the target 19 at the position to be originally irradiated. Is done.

In the present embodiment, the scanner driving mechanism 9 is constituted by the galvanometer and the mirror 18. However, the scanner driving mechanism 9 is constituted by an acousto-optic element, and is acoustically acousto-optic. It is also possible to deflect the laser beam 13 by changing the optical characteristics of the element. In addition to the configuration using the interferometer, the length measurement system may be configured to relatively measure the stage position using a linear scale or the like. Then, the X position detector 11 can have the same configuration as the Y position detector 2 described above. Also, the scanner position setting circuit 6
For example, the configuration may be such that waveform data of a signal supplied to the scanner drive circuit 8 is held in a memory and a signal is generated based on the data. further,
Y position detector 2, stage position setting circuit 4, comparator 5,
The gain adjustment circuit 10, the adder 7, and the like can be formed by one or both of an analog circuit and a digital circuit.

[0029]

As described above, in the optical scanner device of the present invention, the position detecting means detects the position of the stage in the Y-axis direction, and the scanning position correcting means detects the light based on the detection result of the position detecting means. The electric signal given to the optical scanning means is corrected so that the irradiation position moves within a specific range in the Y-axis direction. Then, the light scanning means moves the light irradiation position based on the corrected electric signal. Therefore, even if the stage is displaced in the Y-axis direction due to vibration applied from the outside or the drive of the servomotor accompanying position control, or even if the stage is displaced in the Y-axis direction due to the movement of the stage itself in the X-axis direction, The light irradiation position of light in the Y-axis direction is corrected according to the displacement.
Light is accurately applied to a constant range in the axial direction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an optical scanner device according to the present invention.

FIG. 2 is a side view showing the periphery of a stage.

FIG. 3 is a plan view showing the periphery of a stage.

FIG. 4 is a plan view illustrating scanning of a beam spot on a laser beam irradiation target.

FIG. 5 is a waveform diagram showing a change in displacement of the stage in the Y-axis direction as the stage moves.

FIG. 6 is an explanatory diagram showing a change in the scanning position of the laser beam after correction when the stage is displaced.

FIG. 7 is a waveform diagram illustrating a signal supplied to a scanner drive circuit when an output signal of a scanner position setting circuit is not corrected.

FIG. 8 is a waveform diagram showing a change in an output signal of the gain adjustment circuit when the stage is displaced in the Y-axis direction as the stage moves.

9 is a waveform diagram illustrating an output signal of the adder when an output signal of the gain adjustment circuit changes as shown in FIG.

FIG. 10 is a block diagram showing an example of a conventional optical scanner device.

[Explanation of symbols]

1 ... stage, 2 ... Y position detector, 3 ... CPU,
4 stage position setting circuit, 5 comparator, 6 scanner position setting circuit, 7 adder, 8 scanner drive circuit, 9 scanner drive mechanism, 10 gain adjustment circuit, 11 ... X position detector, 12 ... scan interval detection circuit, 13 ... laser beam, 14 ... optical scanner device, 15 ... Y drive unit, 16 ... X drive unit, 17
… Interference measurement length system, 18… mirror, 19… object, 20… curve, 22… straight line, 23… straight line, 2
4 ... Curve, 26 ... Waveform, 28 ... Curve, 30 ... Line, 32 ... Curve, 101 ... Rectangular area, 102 ... Optical scanner device, 104 ... Line

Claims (7)

[Claims] A stage on which a light irradiation target is placed; a stage driving means for moving the stage in the X-axis direction; and a light irradiation unit for irradiating the target on the stage with light, based on a given electric signal. Light scanning means for moving an irradiation position in a Y-axis direction substantially orthogonal to the X-axis; while moving the stage in the X-axis direction by the stage driving means, light is applied to the object by the light scanning means. An optical scanner device that repeatedly moves the light irradiation position within a specific range in the Y-axis direction by irradiating light, and a position detection unit that detects a position of the stage in the Y-axis direction, and a detection result of the position detection unit. Scanning position correction means for correcting the electric signal given to the light scanning means so that the light irradiation position moves within the specific range. That the optical scanner device. 2. The scanning position correction means receives a signal representing an original position of the stage in the Y-axis direction,
The position of the stage in the Y-axis direction represented by the signal;
2. The optical scanner device according to claim 1, wherein the electric signal is corrected so as to eliminate a difference between the position of the stage in the Y-axis direction detected by the position detection unit. 3. The optical scanner device according to claim 1, wherein said position detecting means comprises an optical interferometer. 4. The optical scanner device according to claim 1, wherein said light scanning means comprises a mirror for reflecting light from a light source, and a galvanometer for driving the mirror. 5. The optical scanning means includes an acousto-optic device,
2. The optical scanner device according to claim 1, wherein light from a light source is deflected acoustically by changing optical characteristics of the acousto-optic element. 6. A second position detecting means for detecting a position of the stage in the X-axis direction, and the stage being substantially constant in the X-axis direction based on a detection result of the stage position by the second position detecting means. A scan interval detecting means for outputting a scan timing signal each time the distance is moved; and outputting the electric signal to the optical scanning means each time the scan interval detecting means outputs the scan timing signal, and outputting the electric signal to the Y-axis direction. 2. The optical scanner device according to claim 1, further comprising: a scanning position setting unit configured to set a scanning position in. 7. The optical scanner device according to claim 6, wherein the scanning position correction unit corrects the electric signal output from the scanning position setting unit.